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51.
The relationship between family influences and participation in violent and nonviolent delinquent behavior was examined among a sample of 362 African American and Latino male adolescents living in the inner city. Participants were classified into three groups: (a) nonoffenders, (b) nonviolent offenders, and (c) violent offenders. Families in the violent delinquent group reported poorer discipline, less cohesion, and less involvement than the other two groups. These results were consistent across ethnic groups. However, the factor Beliefs About Family related to violence risk in opposite directions for African American and Latino families. These results highlight the need to look at ethnic group differences when constructing models of risk. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
52.
Social information processing (SIP) patterns were conceptualized in orthogonal domains of process and context and measured through responses to hypothetical vignettes in a stratified sample of 387 children (50% boys; 49% minority) from 4 geographical sites followed from kindergarten through 3rd grade. Multidimensional, latent-construct, confirmatory factor analyses supported the within-construct internal consistency, cross-construct discrimination, and multidimensionality of SIP patterns. Contrasts among nested structural equation models indicated that SIP constructs significantly predicted children's aggressive behavior problems as measured by later teacher reports. The findings support the multidimensional construct validity of children's social cognitive patterns and the relevance of SIP patterns in children's aggressive behavior problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
53.
The fast evolution of digital video has brought many new multimedia applications and, as a consequence, has increased the amount of research into new technologies that aim at improving the effectiveness and efficiency of video acquisition, archiving, cataloging and indexing, as well as increasing the usability of stored videos. Among possible research areas, video summarization is an important topic that potentially enables faster browsing of large video collections and also more efficient content indexing and access. Essentially, this research area consists of automatically generating a short summary of a video, which can either be a static summary or a dynamic summary. In this paper, we present VSUMM, a methodology for the production of static video summaries. The method is based on color feature extraction from video frames and k-means clustering algorithm. As an additional contribution, we also develop a novel approach for the evaluation of video static summaries. In this evaluation methodology, video summaries are manually created by users. Then, several user-created summaries are compared both to our approach and also to a number of different techniques in the literature. Experimental results show - with a confidence level of 98% - that the proposed solution provided static video summaries with superior quality relative to the approaches to which it was compared.  相似文献   
54.
Two food webs from the Mar Menor coastal lagoon, differing in the distance from the desert-stream through which mining wastes were discharged, were examined by reference to essential (Zn and Cu) and non-essential (Pb and Cd) metal concentrations and stable isotopes content (C and N). The partial extraction technique applied, which reflects the availability of metals to organisms after sediment ingestion, showed higher bioavailable metal concentrations in sediments from the station influenced by the mining discharges, in agreement with the higher metal concentrations observed in organisms, which in many cases exceeded the regulatory limits established in Spanish legislation concerning seafood. Spatial differences in essential metal concentrations in the fauna suggest that several organisms are exposed to metal levels above their regulation capacity. Differences in isotopic composition were found between both food webs, the wadi-influenced station showing higher delta(15)N values and lower delta(13)C levels, due to the discharge of urban waste waters and by the entrance of freshwater and allochthonous marsh plants. The linear-regressions between trophic levels (as indicated by delta(15)N) and the metal content indicated that biomagnification does not occur. In the case of invertebrates, since the "handle strategy" of the species and the physiological requirements of the organisms, among other factors, determine the final concentration of a specific element, no clear relationships between trophic level and the metal content are to be expected. For their part, fish communities did not show clear patterns in the case of any of the analyzed metals, probably because most fish species have similar metal requirements, and because biological factors also intervened. Finally, since the study deals with metals, assumptions concerning trophic transfer factors calculation may not be suitable since the metal burden originates not only from the prey but also from adsorption over the body surfaces and seawater ingestion.  相似文献   
55.
The main purpose of this study is to synthesize reduced graphene oxide (rGO) using graphite (GR) as a starting material. This paper explains didactic step-by-step of the synthesis, the role of each reagent, showing pictures of the entire process and including a well-explained characterization study. The rGO was prepared using modified Hummer’s method, followed by thermal reduction. The materials were characterized from the starting material (GR), through the intermediate material (GO) and finally the material of interest (rGO). Various techniques and procedures were used to characterize the materials such as X-ray diffraction, infrared and Raman spectroscopy, scanning electron microscopy, electrochemical characterization and dispersion analysis. Morphological and structural characterization of the obtained materials suggests that the synthesis and reduction to obtain rGO were effective. The obtained materials were electrochemically evaluated using ferri/ferrocyanide redox probe. The association of chemical oxidation of GR with KMnO4 in the presence of H2SO4 with further thermal reduction makes possible to produce rGO in large scale and with quality as noticed by outstanding electrochemical behavior toward the redox couple [Fe(CN)6]3?/[Fe(CN)6]4? probe.  相似文献   
56.
Journal of Materials Science: Materials in Medicine - A thin endocrown restoration was often applied in endodontically treated teeth with vertical bite height loss or inadequate clinical crown...  相似文献   
57.
Activity in thiophene hydrodesulfurization (HDS) and in the three routes of 2,6-dimethylaniline (DMA) decomposition was examined on Mo sulfide catalysts supported on Al2O3, Nb2O5 and Nb2O5–Al2O3. Catalysts activity is enhanced when Mo phase is deposited on niobium-containing support. For HDS and for the hydrogenation route of DMA decomposition, the niobium-containing support strongly contributes to the catalyst activity whereas the activity of the Mo phase per Mo atom decreases with the increase of niobium amount in the support. By contrast, as for the DMA route, which leads to xylene formation (XYL), the activity of the Mo sulfide phase per Mo atom is strongly enhanced. The electronic properties of the MoS2 phase were studied by means of IR spectroscopy of CO adsorption. Comparison of ν(CO/Mo) wavenumbers reveals an upward shift when Mo sulfide phase is deposited on Nb-containing support. The modification of the electronic properties of the sulfide phase is related to an interaction Mo–Nb either through the formation of a mixed Mo–Nb sulfide phase, or through the interaction MoS2 slabs – support whose strength depends on the support acidity. Hence, the beneficial effect for xylene formation route is attributed to a decrease of the electron density of the Mo sulfide phase that should strengthen the DMA adsorption on the sulfide phase.  相似文献   
58.
Metallurgical and Materials Transactions A - Austenite reversion in Fe–Ni alloys plays a significant role in determining their mechanical properties. Increasing the austenite content in these...  相似文献   
59.
Background: this study aims to investigate the possible association among the histopathologic features of carotid plaque instability, the presence of micro- or macrocalcifications, the expression of in situ inflammatory biomarkers, and the occurrence of the major risk factors in this process in a large series of carotid plaques. Methods: a total of 687 carotid plaques from symptomatic and asymptomatic patients were collected. Histological evaluation was performed to classify the calcium deposits in micro or macrocalcifications according to their morphological features (location and size). Immunohistochemistry was performed to study the expression of the main inflammatory biomarkers. Results: results here reported demonstrated that calcifications are very frequent in carotid plaques, with a significant difference between the presence of micro- and macrocalcifications. Specifically, microcalcifications were significantly associated to high inflamed unstable plaques. Paradoxically, macrocalcifications seem to stabilize the plaque and are associated to a M2 macrophage polarization instead. Discussion: the characterization of mechanisms involved in the formation of carotid calcifications can lay the foundation for developing new strategies for the management of patients affected by carotid atherosclerosis. Data of this study could provide key elements for an exhaustive evaluation of carotid plaque calcifications allowing to establish the risk of associated clinical events.  相似文献   
60.
Trehalose was studied as a drying aid to establish its impact on aroma retention in freeze dried strawberry puree. The evaluation was done by sensory analysis and headspace‐solid phase microextraction‐gas chromatography with a mass detector (HS‐SPME‐GC‐MS); results were compared with those obtained using sucrose and maltodextrin (MD) as drying aids. The carbohydrate used significantly modified the type and concentration of volatiles retained during freeze drying. HS‐SPME‐GC‐MS outcomes showed that the use of trehalose (alone or with MD) resulted in the product with the chromatographic profile most similar to fresh strawberry puree, being different from sucrose and MD. Meanwhile, sensory analysis showed a similarity with the aromatic profiles when using trehalose or sucrose, remaining both different from MD. This study proved that the use of trehalose as a drying aid can be beneficial on volatile aroma retention and that different combinations of organic volatiles can lead to similar sensory profiles.  相似文献   
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